London: Protein, which plays an important role in post diet weight gain, has been discovered by the scientists. The dieters pile on the kilos as soon as they abandon their strict regimen.

A team of international scientists who observed about 100 dieters found a protein called angiotensin-converting enzyme, which regulates blood pressure, was distinctly linked to weight gain post-diet in women.

The finding, they said, could pave the way for a simple blood test that would tell a dieter whether she would require any help to maintain her new shape, before undoing all the good work, according to media reports.

Lead researcher Edwin Mariman of the University of Maastricht, Holland said,"It was a surprising discovery, because until now there has been no clear link between this protein and obesity.

"We do not yet have an explanation for the results, but it does appear that it should be possible within a few years to use this finding to develop a test to show who is at high risk of putting weight back on after a diet."

For their study, the researchers analysed the blood of 96 dieters, aged between 20 and 5 years, who had already lost weight. Half successfully kept it off, or lost even more. But the others regained the lost pounds.

The study revealed that 80 per cent of the dieters who piled on the pounds after dieting had high levels of angiotensin-converting enzyme.

Though the mechanism behind the protein affecting the dieters is ambiguous, researchers believe that it may be intruding with the hormones that regulate how full we feel by making the body store extra fat and water.

Research has shown the repeated rapid weight gain and loss associated with dieting, called yo-yo dieting which can double the risk of death from heart disease, including heart attacks, and the risk of premature death in general.

It has also been linked to stroke and diabetes and shown to suppress the immune system, making the body more vulnerable to infection.

Dr Susan Jebb, one of the British experts on the research team, stressed that much more work needs to be done before a blood test for dieters is developed.

"Yo-yo dieting is psychologically upsetting for people and repeated cycles which feel like failure breed a lack of self-confidence."

The new study has been published in the journal 'PLoS One'.